In modern software environments, memory usage and hard disk accesses can contribute significantly to application and website startup time and to the time it takes for a program to become responsive to a user action. Disk access can contribute to latency because of the time it takes to position a read/write head over a requested track. Similarly, memory usage can contribute to latency because of the time it takes to move data into and out of memory and because of transfers of data from one type of memory to another type of memory.